Sputumisexpectoratedmucus.However,inadditiontomucus,sputumcontainsserumproteins,lipids,electrolytes,Ca++ ,DNAfromdegeneratedwhitebloodcells(collectivelyknownasbronchial secretions),andextrabronchialsecretions;includingnasal,oral,lingual,pharyngeal,andsalivarysecretions.Thecolorofsputumismorecloselycorrelatedwiththeamountoftimethatithasbeenpresentinthelowerrespiratorytractthanwiththepresenceofinfection.Althoughnotpreciselyidentifiablewithdiseasediagnosis,thecolorofsputumcanbeinformativeinhelpingleadtoadiagnosisandstageofdisease.Mucushasmanycolors:white,yellow,green,red,pink,brown,gray,andblack.Thecolorationiscommonlyduetothetypeofcellpresentintheairways(inflammatorycells,suchasneutrophilsoreosinophils,orredbloodcells)andhowlongtheyhavebeenthere.Clearorcloudywhite thinmucusisconsiderednormal;however,ifamountsandthicknessareincreased,itmayrepresentanearlysignofinfection.Thickwhitemucuscanbetheonlyidentifiablefeatureofgastroesophagealrefluxdiseasecausedbygastricacidrefluxintotheairways.Yellow andgreen colorationofmucusisduetothepresenceandbreakdownofneutrophilsandeosinophilsininfectiousandallergicdiseases.Yellowistypicallyassociatedwithmoreacutedisease(infection,allergy)andgreenusuallyindicatesamorechronicstagewiththepresenceofbacteria(chronicbronchitis,bronchiectasis,cysticfibrosis,andlungabscess).Red mucusindicatesthepresenceofredbloodcellsintheairwaysandisassociatedwithpneumococcalpneumonia,lungcancer,tuberculosis,andpulmonaryemboli.Pink mucusistypicallyassociatedwiththebreakdownofeosinophilsinindividualswithallergies.Gray,brown,andblackmucusisoftenassociatedwithcigaretteormarijuanasmoking,cocaineuse,airpollution(workplaceenvironment,suchascoalmines),andoldblood.
1000 strokes per minute, with a power forward stroke and a slow return or recovery stroke. During their power forward stroke, the tips of the cilia extend upward into the viscous mucus layer and thereby move it and the entrapped particles. On the reverse beat, the cilia release the mucus and withdraw completely into the sol layer. Cilia in the nasopharynx beat in the direction that propels the mucus into the pharynx, whereas cilia in the trachea propel mucus upward toward the pharynx, where it is swallowed.
In general, deposition of particles in the lung depends on the particle’s size, density, and shape; the distance over which it has to travel; airflow speed; and the relative humidity of the air. The four major mechanisms for deposition are impaction, sedimentation, interception, and brownian movement. Particle characteristics and properties, which influence the mechanism of deposition, are listed in 26.2 . In general, particles larger than 10 µm are deposited by impaction in the nasal passages and do not penetrate into the lower respiratory tract. Particles 2 to 10 µm in size
Sedimentation0.2to2.0InterceptionNABrownianmovement<0.2
NA,notapplicable.